IME Proprietary
EPRC – 12
Project Proposal
Power Electronics Packaging
Solutions for Device Junction
Temperature over 220oC
15th August 2012
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IME Proprietary
Motivation
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Increased requirements of high power semiconductor device module for future
automotive, aerospace and green & renewable energy industry
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Emerging wide band gap power devices : SiC and GaN can be operated >220oC
Renewable energy
Source: Yole
Electronic Vehicle
Source: Nissan
Electronic Railway
Source: Infineon
Aerospace
Hybrid Vehicle
Page 2
Source: Toyota
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IME Proprietary
Technology Trends
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Technology trends for high power module and discrete :
 High temperature endurable materials >220oC (silver sintering, encapsulations)
 High reliable and low stress interconnections (foil interconnects, ultrasonic bonding)
 Thermal cooling solution (Dual-side cooling / micro-channel cooling )
Source: Yole
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IME Proprietary
Challenges to be Addressed
Power Source Interconnection
Substrate (DBC)
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Power cycling endurance
Temp cycle endurance
Process optimization
inter-metallic diffusion
Thermal & Electrical properties
Temp cycling endurance
Adhesion with Encapsulation
Adhesion between Cu/Ceramic
Surface finish
Thermal & Electrical properties
Power Module
Encapsulation Materials
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Thermal endurance >220C
Void free processing
Lower stress (CTE, Modulus)
High power insulation
Moisture barrier
Delamination free
Passive component attach
Plastic case
Encapsulations
Diode
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Wire
IGBT
Passive
DBC substrate
Thermal endurance >220C
Void free processing
Temp cycle endurance
Electrical conductive
Metallization > 220C
Base plate
Power Device Attach
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Thermal endurance >220C
Void free processing
Lower stress (CTE, Modulus)
Electrical conductive
Die backside metallization
Power Discrete
Thermal interface materials
Wire
IGBT
Lead frame
Heat spreader
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Thermal endurance > 220C
Temp cycle endurance
Delamination & fracture
Thermal conductivity
Base plate (system board)
Reliability testing methodologies
• Reliability test spec
• Reliability testing method
• Failure Analysis / reliability model
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Modeling and predictions
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Thermal characterization
Mechanical characterization
Electro-thermal-mechanical coupling
Reliability model (power cycling)
IME Proprietary
Project Proposal
Objective
Development and characterization of power semiconductor packages for high junction
temperature endurable (>220oC) solutions for next generation devices, including the following:
Material solutions for TV1 and TV2
 High temperature endurable die attach (Ag sintering, TLP bonding, Cu-Cu bonding)
 DBC surface finish option (Ni/Au finish, ENIG )
 High temperature endurable encapsulation materials (High Tg EMC)
 Cu based interconnection through EMWLP RDL process
Thermal management solutions for TV1 and TV2
 Dual side cooling structure package development and packaging process optimization
 High temperature endurable, high conductive TIM materials ( Ag sintering )
Package characterization and Reliability for TV1 and TV2
 Mechanical &Thermal modeling and characterization
 Power cycling modeling : electro-thermal- mechanical coupled analysis
* To be finalized with members input
 Reliability and failure analysis
Conventional Power Module
TV1* : Novel Dual side cooling Power Module
Heat spreader
Plastic case
Encapsulations
Diode
Wire
IGBT
Passive
DBC substrate
Base plate
Wire
Lead frame
Heat spreader
Base plate (system board)
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IGBT
Diode
Heat spreader
Conventional Power discrete *
IGBT
Top RDL layer
* Conventional test vehicle with new material option can be considered
as project test vehicle on the basis of members assembly support
TV2* : Novel Dual side cooling Power Discrete
Heat spreader
IGBT
Heat spreader
IME Proprietary
Design Optimization and Reliability Prediction for
Power Module/Discrete with Dual Side Cooling
 Structural modeling and interconnection
life prediction for novel dual side cooling
power module
 Power source/gate/drain RDL design
optimization for stress minimization
 Interconnection fatigue life prediction (plastic
constitutive model for Cu RDL)
 Packaging material properties effect on the
investigation
 Electro-thermo-mechanical coupled power
cycling impact modeling
Ref. Hua Lua et al. “Lifetime Prediction for Power Electronics
Module Substrate Mount-down Solder Interconnect”
Proceedings of HDP’07
 Thermal modeling and characterization
 Thermal resistance modeling for selected
material set and design
 Experimental Thermal resistance
Rthjc characterization
 Liquid based active cooling investigation
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Ref. Institute of Microelectronics
Dual side cooling effect Tjmax decreased compared with
single side cooling
IME Proprietary
High Temperature Endurable Materials for Power
Module with Tjmax> 220oC
 High Temperature Power Device
Ref. Institute of Microelectronics
Micro Ag particles sintered by pressure less process
interconnection development
 High temperature endurable die attach (drain)
 Micro/Nano Ag sintering (pressure less)
 TLP bonding : Cu-Sn(415oC), Ag-Sn(480oC)
 Direct Cu-Cu ultrasonic bonding
 Device backside metallization
 Substrate surface finish option (Ni/Au finish, ENIG)
 Power source and gate interconnect through
TLP bonding (Cu-Sn) used in Infineon XT modules in 2010
Electrolytic Cu Patterning
 High Temperature Endurable Compounds
Development
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High glass transition temperature (Tg >200oC)
High thermal conductive compounds (~3W/m-K )
Compatible with Wafer level fan-out process
Investigation on thermal degradation (< 3%wt) with
continuous exposure to 220oC
Low stress, low thermal mismatch
Chin-Lung Chiang et.al “Thermal stability and degradation
kinetics of novel organic/inorganic epoxy hybrid…”
Thermochimica Acta 453 (2007)
thermal degradation
kinetics for epoxy
IME Proprietary
High Temperature Endurable Materials for Power
Module with Tjmax> 220oC
 Thermal Interface Material investigation
 High conductive /temperature endurable
 Metallic TIM (Ag sintering) with high power insulation
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Source : Danfoss
Ag sintering for TIM
layer (Al2O3)
Polymeric TIM with conductivity > 4W/m-K
Thickness control
Thermal performance consistency investigation after
reliability test
TIM layer crack propagation
 High Temperature Endurable Dielectric
passivation layer
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High glass transition temperature (Tg >200oC)
BCB, Polyimide photo sensitive PR
Compatible with Wafer level fan-out process
Investigation on thermal degradation (< 3%wt) with
continuous exposure to 220oC
Low stress, low thermal mismatch
Source : Danfoss
IME Proprietary
Dual Side Cooling Power Module Process
Optimization and Reliability Assessment
 Dual side Cooling Power Module Assembly
IME’s Novel Dual side Cooling Power
Module Assembly Process
Process development
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Cu clip (Ag plated) attachment / alignment
Evaluation of molding material Liquid, Granular
Process condition (Temperature, time, pressure)
Module shift analysis & control
Die/ module pick & place tolerance
Minimum clearance between die
Warpage control
Heat spreader attach and TIM process
 Reliability Assessments for High Power
Application
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Temperature cycling (Test condition : TBD*1)
High Temperature Storage ( 220oC/ 1000 hrs )
HAST (non-biased)
Power Cycling test (optional*2)
Failure analysis
*1 To be finalized with members input
*2 Need member’s support on actual SiC wafer and testing
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Tilo Poller et al. “Influence of thermal cross-couplings on
power cycling lifetime of IGBT power modules” CIPS 2102
Power cycling : IGBT with 300W,10Hz
IME Proprietary
Possible Research Outcome*
 Thermal and Structural optimization and life prediction for novel dual
side cooling power module
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Interconnection fatigue life prediction (plastic constitutive model for Cu RDL)
Packaging material properties effect on the test vehicle
Thermal modeling characterization for selected material set and test vehicles
Electro-thermo-mechanical coupled power cycling impact analysis
 Tjmax >220oC : High Temperature Endurable Power Device Packaging
material Solutions (interconnect/encapsulation/TIM)
 High temperature endurable die attach material characterization using Micro/Nano
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Ag sintering, TLP bonding, Direct Cu-Cu ultrasonic bonding
Power source and gate interconnect through Electrolytic Cu Patterning
Wafer level Fan-out compatible compounds characterization
TIM process optimization for dual side application
 Dual side Cooling Power Module Assembly Process development
 Copper clip (Ag plated) attachment / alignment
 Mold Process condition optimization (Temperature, time, pressure)
 Heat spreader attach and TIM process
 Reliability Assessments & F/A for Novel High Power Module
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Temperature cycling
High Temperature Storage / Low Temperature Storage
HAST (non-biased)
Power Cycling test (optional)
Failure analysis
Page 10 * To be finalized
IME Proprietary
Project Flow
Members Inputs
Scope Planning
Material investigation
Finalize Project scope and test vehicles
specifications
Process and assembly
Identify high thermal endurable
materials and evaluation
(Members to provide inputs)
Thermal Modeling &
Simulation Analysis
TV1,2 Dual cooling effect
Power cycling modeling
Electro-Thermo-mechanical
Mechanical Modeling &
Simulation Analysis on stress and
reliability
Test methodologies
(Thermal and Reliability )
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Thermal performance testing
Dual side cooling effect analysis
with active cooling
Final reliability
Initial Material evaluation and quick
reliability test
Power module EWLP Assembly
process optimization. Device chip*
(fabrication/purchase)
TV1 Thermal performance sample matrix
TV2 Thermal performance sample matrix
TV2 Reliability test sample matrix
TV1 Reliability test sample matrix
Project Time line and
schedule :
Nov 2012 to June 2014
Modeling & characterization
EWLP process
modeling –
flow/Warpage
Note: *Electric testing will be carried
out based on device chip availability
Reliability testing
Failure analysis and report writing
IME Proprietary
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